Touch screen, as an input medium, can facilitate a user's operation in a better manner as compared with a keyboard or mouse. Depending on different implementation principles, the touch screens may include a resistive touch screen, a capacitive touch screen, a surface-acoustic-wave touch screen and an infrared touch screen. Currently, the resistive and capacitive touch screens have been widely used.
A mutually capacitive touch screen has attracted more and more attentions due to its advantages such as high sensitivity and a multi-point touch function. As its basic principle, a voltage is applied to a driving line side and a signal change is detected at a detection line side. A driving line is configured to determine an X-axis coordinate, and a detection line is configured to determine a Y-axis coordinate. During the detection, the driving lines are scanned progressively in an X-axis direction, and a signal from each detection line is read when scanning each row of the driving lines. All junctions in each row and each column may be scanned at a time, and X*Y signals may be obtained. This detection mode may be used to determine the coordinates of multiple points, so it is able to achieve the multi-point touch function. FIG. 1 shows an equivalent circuit model, which includes a signal source 101, a driving line resistor 103, a mutual capacitor 102 between the driving line and the detection line, a parasitic capacitor 104 among the driving line, the detection line and a common electrode layer, a detection line resistor 105, and a detection circuit 106. When a screen is touched by a finger, a part of the current flows into the finger, which is equivalent to a change in the mutual capacitor 102 between the driving line and the detection line. A resultant tiny change in the current is then detected at a detection end by the detection circuit 106.
In an existing touch screen, there is a very large coupling capacitance between a transmitter electrode (TX) and/or a receiver electrode (RX) and electrodes on an array substrate. During the deflection of liquid crystals, the touch and detection operations will be adversely affected, and thereby the quality of the touch screen will be deteriorated.